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IC Wall Outlet Adapter 



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IC Wall Outlet Adapter 

Written By: Jack Oster 



TOOLS: 



Drill (1) 

Multimeter or Continuity Tester (1) 
Soldering/desoldering tools (1) 
Wire cutter/stripper (1) 



PARTS: 



Extension cord (1) 

Transformer (1) 

Schottky signal diode (4) 

A bridge rectifier will work as well. 

LM7805 voltage regulator (1) 

Capacitor (4) 

2 mylar film capacitors, both . 1AjjF, and 

2 electrolytic capacitors, both IOOAjjlF 

• Project box (1) 

Perfboards (1) 



SUMMARY 

I like to build a lot of circuitry, but the voltage regulators that most IC's require get annoying 
when you have to keep on buying them and putting them into each board you want to power. 
This is a very simple little device that will take the voltage coming from a power outlet in 
your home and change it into a steady 5v, good enough to power even the most picky of 
circuits. 



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IC Wall Outlet Adapter 



Step 1 — IC Wall Outlet Adapter 




• Start by taking the extension cord 
and cutting off the end of it. If the 
power cord is grounded, then 
ignore the wire that leads to ground 
for now. Take your multimeter and 
measure the voltage across the hot 
and neutral wires, while the cord is 



& 



plugged in. 

• The 120v AC coming from 
the frayed wire is very 
dangerous! Handle with extreme 
caution, as the amperage could kill 
you. 

• If this doesn't work, something is 
wrong with your extension cord and 
you should use a different one. 



Step 2 



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• Using alligator clips, hook up the 
hot and neutral ends of the 
extension cord to the primary leads 
of the transformer. With the 
multimeter, measure the voltage 
across one of the hot secondary 
leads and the neutral secondary 
lead. 

• If this voltage is higher than 9v, 
you'll need a heat-sink for the 
voltage regulator. 



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IC Wall Outlet Adapter 



Step 3 — Build the bridge rectifier 




• Break off a piece of perfboard at 
least 18x8. Sand the edges 
smooth. 

• If you have a preassembled bridge 
rectifier, you can skip this step. 
Insert four diodes across the top, 
with the cathode mark all facing 
toward the middle of the board. 
Strip a piece of wire and connect 
the anode (unmarked) side of the 
two diodes on the ends. 

• Now hook up the two hot 
secondary leads to the junction 
between the anode and cathode of 
two diodes, so there's an anode 
and cathode connected to both of 
the secondary leads. Power up the 
transformer, and measure voltage 
DC: negative at the ends of the 
diodes, and positive at the middle 
of the diodes. 



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IC Wall Outlet Adapter 



Step 4 — Assemble the voltage regulator 




• Insert the voltage regulator into the 
circuit, input facing the diodes, and 
solder it down. Push in one 
electrolytic capacitor and a film 
capacitor on the input lead and 
ground lead. Negative on the 
electrolytic connects to the 
common ground lead. 

• Push in and solder the other two 
capacitors on the output side where 
the electrolytic's negative lead will 
attach to ground. 



Step 5 — Test the circuit 




• Using a jumper wire, connect the 
input of the voltage regulator to the 
middle of the diodes and the 
common ground to either of the 
ends. 

• Hook up the transformer to the 
diodes (or bridge rectifier) again 
and test the voltage coming out of 
the voltage regulator. It should read 
a good 5v. If it doesn't, power down 
and look for mistakes in the wiring. 

• If it does work, hook up a long red 
wire to the output of the voltage 
regulator and a black wire to 
anywhere that is connected to 
negative. 



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IC Wall Outlet Adapter 



Step 6 — Mount it in a project box 




• Using electrical tape, wrap up the 
secondary neutral lead of the 
transformer, so that it doesn't 
interfere with anything. Push the 
primary leads of the transformer 
out one of the holes and solder it to 
the extension cord, and then 
wrapping the joint in electrical tape. 



Step 7 




• You should now have a fully 
functional AC-to-5V wall adapter. 
Use it for whatever you like. 



You should be able to run all circuits that require 5v off of this little device. 



This document was last generated on 201 2-1 1 -01 04:25:08 PM. 



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